Google Sheets - sum a cell from a dynamic list of sheets with vlookup

Question

I have a Google Sheet that I update with a new sheet every two days or so and title the name of the sheet the date that it is created. For organizational reasons, I do not want to combine all of the information into one sheet and parse it elsewhere, even though it would make this so much simpler.

I'd like to provide a named range of different sheet names, and have a script, function, etc go to each sheet, grab the contents of a cell and sum them. Bonus points if vlookup can be integrated to ensure that the right cell is being referenced.

So, for example:

named range = '7/3/21','7/1/21'
=sum('7/3/21'!B12,'7/1/21'!B12)

This is simple enough, but I don't want to alter this every time a new sheet is added to reference the new sheet.

In my mind it would look something like:

=sum(vlookup(A1(INDIRECT(NamedRange1&"!c1"))

where:
A1 = the name I want to lookup on the other sheets
NamedRange1 = range of cells that correspond to all of the different sheets
C1 = the cell that I want to add across all the other sheets.

Answer 1

function sumacellfromlistofsheets(obj) {
  const listofsheets = obj.list;
  const ss = SpreadsheetApp.getActive();
  const shts = ss.getSheets().filter(sh => ~obj.list.indexOf(sh.getName()));
  let sum = 0;
  shts.forEach( sh => {
    sum += sh.getRange(obj.cellinA1Notation).getValue();
  });
}